Work vehicle

ABSTRACT

Provided is a work vehicle in which a positioning antenna can be installed above a roof plate of a cab at an accurate position and in a proper attitude while preventing a positioning accuracy from being decreased by vibrations. The work vehicle includes a first mount member, a second mount member and a positioning antenna. The first mount member includes a left-side member fixed on the roof beam at the left side and a right-side member fixed on the roof beam at the right side. The second mount member is disposed above the roof plate across the left-side member and the right-side member. The positioning antenna is mounted on the second mount member.

TECHNICAL FIELD

The present invention relates to a work vehicle, and in particular, relates to a work vehicle equipped with a cab to be boarded with an operator.

BACKGROUND ART

Information-and-Communication-Technology intensive constructions have been performed on a work vehicle having a work implement by using a satellite navigation system to determine a position of the work implement in real time so as to improve work efficiency thereof. Conventionally, there has been disclosed a work vehicle which has a pole disposed on an upper edge of a work implement, and on an upper end of the pole, a GNSS (Global Navigation Satellite System) antenna is installed (for example, see Japanese Patent Laying-Open No. 10-38570 (PTD 1)).

In the case where the work vehicle is a bulldozer, in performing operations such as dozing and grading, the work implement is subjected to great vibrations, which decrease a positioning accuracy of the GNSS antenna disposed on the work implement. When the work implement is subjected to vibrations, the pole may vibrate, and an antenna cable connected to the GNSS antenna may contact earth or sands. Accordingly, a technique has been proposed to install the GNSS antenna on a roof of a cab to be boarded with an operator.

CITATION LIST Patent Document

-   PTD 1: Japanese Patent Laying-Open No. 10-38570

SUMMARY OF INVENTION Technical Problem

In a conventional work vehicle, a roof surface of a cab is formed by fixing a planar roof plate on frame-shaped beams. The roof plate is convexly curved upward to prevent water from being accumulated on a top surface thereof. Thereby, when installing a positioning antenna on the top surface of the roof plate, since the roof plate is curved, it is difficult to install the positioning antenna at an accurate position and in a proper attitude.

The present invention has been accomplished in view of the aforementioned problems, and it is therefore an object of the present invention to provide a work vehicle in which a positioning antenna can be installed above a roof plate of a cab at an accurate position and in a proper attitude while preventing a positioning accuracy from being decreased by vibrations.

Solution to Problem

The work vehicle of the present invention includes a work implement, and a cab to be boarded with an operator to operate the work implement. The cab includes a lateral pair of roof beams disposed respectively on the top of both side surfaces of the cab and a roof plate supported respectively by the pair of roof beams. The work vehicle further includes a first mount member, a second mount member and a positioning antenna. The first mount member includes a left-side member fixed on the roof beam at the left side and a right-side member fixed on the roof beam at the right side. The second mount member is disposed above the roof plate across the left-side member and the right-side member. The positioning antenna is mounted on the second mount member.

According to the work vehicle of the present invention, the positioning antenna is installed relatively on a strong structure constructed by the roof beams of the cab through the intermediary of the first mount member and the second mount member, and thereby, it is possible to prevent the positioning accuracy from being decreased by vibrations and it is possible to install the positioning antenna above the roof plate at an accurate position and in a proper attitude.

In the work vehicle mentioned above, the roof plate is convexly curved upward. Thus, by fixing the first mount member on the lateral pair of roof beams and disposing the second mount member on the first mount member, it is possible to dispose the positioning antenna without being affected by the shape of the roof plate. Thereby, the positioning antenna can be installed with more certainty above the roof plate at an accurate position and in a proper attitude.

In the work vehicle mentioned above, a gap is formed between the second mount member and the roof plate. Thereby, it is possible to prevent the second mount member from being interfered by the roof plate, enabling the positioning antenna to be mounted on the second mount member at an accurate position and in a proper attitude.

The work vehicle mentioned above further includes an antenna cable connected to the positioning antenna. A part of the antenna cable is disposed inside the gap formed between the second mount member and the roof plate. Thereby, the part of the antenna cable is disposed below the second mount member and invisible from the outside, improving the outer appearance of the work vehicle.

In the work vehicle mentioned above, the left-side member and the right-side member are welded on upper surfaces of the roof beams. Thereby, there is no need to perform a processing such as perforating holes in the roof beams in order to fix the left-side member and the right-side member on the roof beams. Accordingly, it is possible to maintain the strength of the roof beams, preventing the strength of the cab from being decreased with certainty.

In the work vehicle mentioned above, the cab further includes a width-direction roof beam disposed on the top of the cab and extending in the width direction of the work vehicle. The first mount member further includes a width-direction member fixed on the width-direction roof beam. The second member is supported by the width-direction member. Thereby, the second mount member is supported by the left-side member, the right-side member and the width-direction member, enabling the second mount member to be disposed above the roof plate more stable.

In the work vehicle mentioned above, the second mount member has an antenna installation surface. The positioning antenna is mounted on the antenna installation surface. The antenna installation surface has a planar shape. Thereby, it is easier to mount the positioning antenna on the antenna installation surface at an accurate position and in a proper attitude.

Advantageous Effects of Invention

According to the present invention as described above, it is possible to install the positioning antenna above the roof plate of the cab at an accurate position and in a proper attitude while preventing the positioning accuracy from being decreased by vibrations.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view schematically illustrating a structure of a work vehicle according to an embodiment of the present invention;

FIG. 2 is an exploded perspective view schematically illustrating the structure of the work vehicle according to an embodiment of the present invention;

FIG. 3 is a perspective view schematically illustrating a structure of a cab of the work vehicle according to an embodiment of the present invention;

FIG. 4 is a sectional view schematically illustrating a roof plate along a line IV-IV in FIG. 3;

FIG. 5 is a perspective view schematically illustrating a structure of a mount unit for mounting a positioning antenna according to an embodiment of the present invention;

FIG. 6 is an exploded perspective view schematically illustrating the mount unit for mounting the positioning antenna according to an embodiment of the present invention;

FIG. 7 is a perspective view schematically illustrating a state where a first mount member is fixed on a roof portion of the cab;

FIG. 8 is a sectional view schematically illustrating the mount unit along a line VIII-VIII in FIG. 6;

FIG. 9 is a sectional view schematically illustrating the first mount member along a line IX-IX in FIG. 7;

FIG. 10 is a sectional view schematically illustrating the first mount member along a line X-X in FIG. 7; and

FIG. 11 is a bottom view schematically illustrating a structure of a second mount member.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

With reference to FIG. 1, a bulldozer 30, which serves as a work vehicle of the present invention, mainly includes a cab 1, an engine compartment 34, a hydraulic oil tank module 35, a pair of track frame modules 37, and a dozing blade 38. Cab 1 is a box-shaped structure which forms an interior room space for an operator OP operating bulldozer 30 to enter. With reference to FIG. 2, bulldozer 30 further includes a vehicle frame 31, an engine 32, an engine cooling module 33, and a fuel tank module 36.

Vehicle frame 31 has a front end and a rear end. Cab 1 is mounted on vehicle frame 31 between the front end and the rear end of vehicle frame 31. Cab 1 is equipped with a seat for operator OP to sit on, a manipulation mechanism such as a pedal and a lever, and an instrument panel or the like. Operator OP boards cab 1 to drive bulldozer 30 and operate dozing blade 38. In the present embodiment, when operator OP is seated in cab 1, the direction to a left side of operator OP, the direction to a right side thereof, the direction to a front side thereof, and the direction to a rear side thereof are referred to the left side, the right side, the front side and the rear side, respectively.

Engine 32 is mounted on vehicle frame 31 at a front position of vehicle frame 31 ahead of cab 1. Engine compartment 34 covers engine 32. Cab 1 is disposed posterior to engine 32 covered by engine compartment 34.

Hydraulic oil tank module 35 is configured to store hydraulic oil for activating a work implement such as dozing blade 38 or the like of bulldozer 30, and is disposed at one side of cab 1. Fuel tank module 36 is configured to store fuel to be supplied to engine 32, and is disposed at the other side of cab 1.

Engine cooling module 33 is configured to cool engine 32 or the like, and is mounted on vehicle frame 31 at the rear end of vehicle frame 31. A cooling fan of engine cooling module 33 may be electrically driven by an electric motor or hydraulically driven by a hydraulic motor or the like, independently of engine 32. It is preferable that the fan is driven hydraulically at a variable speed. Engine cooling module 33 is disposed posterior to cab 1 at a position between a rear end of hydraulic oil tank module 35 and a rear end of fuel tank module 36.

The paired track frame modules 37 are disposed at the left side and the right side of vehicle frame 31, respectively. Dozing blade 38 is disposed anterior to the front end of vehicle frame 31. Operator OP inside cab 1 operates dozing blade 38 by using the manipulation mechanism to perform operations such as dozing and grading and the like.

A positioning antenna 50 configured to determine a present position of the work implement is installed on a roof portion of cab 1. Cab 1 includes a roof plate 2 to be described hereinafter, and positioning antenna 50 is disposed above roof plate 2. Through the intermediary of a first mount member 10 and a second mount member 20, which will be described hereinafter, positioning antenna 50 is mounted upper to the roof portion of cab 1.

Positioning antenna 50 is configured to receive radio waves containing a navigation signal from satellites 121 and 122. A controller and a display (both not shown) are disposed in cab 1. The controller, based on the signal received by positioning antenna 50, computes a present position of positioning antenna 50, and thereafter, based on the computation result, computes a present position of dozing blade 38 accurately and precisely. The present position of dozing blade 38 is updated and displayed on the display in real time, and thereby, operator OP boarding in cab 1 can confirm the operation status constantly.

With reference to FIG. 3, cab 1 includes a plurality of pillars. The plurality of pillars are disposed with the longitudinal direction of each pillar extending in the vertical direction. The plurality of pillars include a pair of front pillars 3 disposed in the front of cab 1, a pair of rear pillars 5 disposed in the rear of cab 1, and a pair of central pillars 4 disposed in a center portion of cab 1 in the anteroposterior direction. Front pillars 3, central pillars 4 and rear pillars 5 are arranged in a sequence from the front of cab 1 toward the rear thereof. End portions of the pair of central pillars 4 and the pair of rear pillars 5, respectively, are welded on a floor plate (not shown).

Cab 1 further includes a left-side roof beam 7 joining both upper ends of central pillar 4 and rear pillar 5 at the left side, and a right-side roof beam 8 joining both upper ends of central pillar 4 and rear pillar 5 at the right side. Thus, cab 1 includes a lateral pair of roof beams disposed at upper ends of both sides of cab 1. Left-side roof beam 7 and right-side roof beam 8 are arranged to have the longitudinal direction thereof extending in the anteroposterior direction. Left-side roof beam 7 is supported by central pillar 4 and rear pillar 5 at the left side. Right-side roof beam 8 is supported by central pillar 4 and rear pillar 5 at the right side.

Cab 1 further includes a width-direction roof beam 9 a joining upper ends of the pair of rear pillars 5, respectively. Width-direction roof beam 9 a is arranged to have the longitudinal direction thereof extending in the width direction (lateral direction) of cab 1. Both ends of width-direction roof beam 9 a are connected respectively to rear ends of left-side roof beam 7 and right-side roof beam 8 and fixed through welding. Width-direction roof beam 9 a is disposed on the top of cab 1 at the rear side.

Cab 1 further includes a width-direction roof beam 9 b joining upper ends of the pair of central pillars 4, respectively. Width-direction roof beam 9 b is arranged to have the longitudinal direction thereof extending in the width direction (lateral direction) of cab 1. Both ends of width-direction roof beam 9 b are connected respectively to the ends of left-side roof beam 7 and right-side roof beam 8 at the front side and fixed through welding. Left-side roof beam 7, right-side roof beam 8 and width-direction roof beams 9 a and 9 b constitute a part of structural materials for the roof of cab 1.

Cab 1 further includes roof plate 2 made from a plate member. Roof plate 2 forms a roof surface of cab 1. Roof plate 2 is supported by the lateral pair of roof beams, i.e., left-side roof beam 7 and right-side roof beam 8, and width-direction roof beams 9 a and 9 b, respectively. A left-side edge of roof plate 2 is disposed on left-side roof beam 7, and fixed on left-side roof beam 7 through welding. A right-side edge of roof plate 2 is disposed on right-side roof beam 8, and fixed on the upper surfaces of right-side roof beam 8 through welding. A rear-side edge of roof plate 2 is disposed on width-direction roof beam 9 a, and fixed on the top surfaces of width-direction roof beam 9 a through welding.

As mentioned above, cab 1 has a structure obtained by joining the pair of central pillars 4, the pair of rear pillars 5, the floor plate, left-side and right-side roof beams 7 and 8, and width-direction roof beams 9 a and 9 b through welding, respectively. In addition, such structure serves as a rollover protection structure. The rollover protection structure has an improved structural strength and is configured to protect operator OP sitting with a seat belt on the seat in cab 1 when the work vehicle rolls over.

FIG. 4 illustrates a sectional view along a line IV-IV in FIG. 3. With reference to FIG. 4, roof plate 2 includes an upper surface 2 a and a lower surface 2 b. Upper surface 2 a and lower surface 2 b form primary surfaces of plate-shaped roof plate 2. Roof plate 2 has a convex shape protruding upward. Roof plate 2, which has a shape by bending a flat plate having primary surfaces in planar shape into the convex shape, is mounted on the upper surfaces of left-side roof beam 7, right-side roof beam 8 and width-direction roof beams 9 a and 9 b with the convex shape formed according to the bending deformation of the flat plate pointing upward. Upward curving edges of roof plate 2 are welded on left-side roof beam 7, right-side roof beam 8 and width-direction roof beams 9 a and 9 b, and thereby, roof plate 2 is fixed at cab 1, with the central portion thereof protruding upward higher than the edges thereof.

Hereinafter, a structure in which positioning antenna 50 is mounted above roof plate 2 of cab 1 will be described in detail. With reference to FIG. 5, positioning antenna 50 includes an antenna main body 51 having a receiving function, and a support member 52 supporting antenna main body 51 from below. Support member 52 is installed on second mount member 20. Positioning antenna 50 is mounted on second mount member 20 at a central portion. Positioning antenna 50 is designed to be detachable from second mount member 20 so as to comply with height regulations in transporting bulldozer 30.

Second mount member 20 is formed with a plurality of holes 25 and 26. Holes 25 and 26 are formed in such a way that they penetrate second mount member 20 in the thickness direction thereof. Holes 25 are formed at both lateral edges of second mount member 20. Second mount member 20 is fixed to left-side roof beam 7 and right-side roof beam 8 through bolts penetrating holes 25 in the vertical direction. Holes 26 are formed at the rear edge of second mount member 20. Second mount member 20 is fixed to width-direction roof beam 9 a through bolts penetrating holes 26 in the vertical direction. If the fixing through bolts is disengaged, it is possible to detach second mount member 20 from the roof of cab 1; thereby, in transporting bulldozer 30, positioning antenna 50 and second mount member 20 may be detached from cab 1 as a whole.

Positioning antenna 50 is connected with an antenna cable 56. Antenna cable 56 is an electric cable configured to perform data communications with and supply power to positioning antenna 50. Second mount member 20 is formed with a through hole 27 penetrating second mount member 20 in the thickness direction thereof nearby the position where positioning antenna 50 is mounted. Through hole 27 has a diameter sufficiently greater than the outer diameter of antenna cable 56. Second mount member 20 includes an antenna cable outdrawing member 28 disposed above left-side roof beam 7. Antenna cable outdrawing member 28 is formed with a through hole 29. Through hole 29 has a diameter substantially equal to the outer diameter of antenna cable 56.

Antenna cable 56 is provided with a stopper member 57 which is disposed around an end portion of the antenna cable to which position antenna 50 is connected. Stopper member 57 is configured to prevent antenna cable 56 from getting disengaged from positioning antenna 50 by preventing a nut used to join antenna cable 56 and positioning antenna 50 from loosing.

With reference to FIG. 6, a left-side member 17 is fixed on the upper surfaces of left-side roof beam 7. Similar to left-side roof beam 7, left-side member 17 is arranged to have the longitudinal direction thereof extending in the anteroposterior direction. A right-side member 18 is fixed on right-side roof beam 8. Similar to right-side roof beam 8, right-side member 18 is arranged to have the longitudinal direction thereof extending in the anteroposterior direction. Second mount member 20 is disposed above roof plate 2 across left-side member 17 and right-side member 18, and supported by both left-side member 17 and right-side member 18.

Left-side member 17 and right-side member 18 are formed with a plurality of screw tap holes 15. Screw tap holes 15 are formed at positions in respective correspondence with holes 25 formed in second mount member 20. Screw tap holes 15 are formed by boring from upper surfaces of left-side member 17 and right-side member 18 downward to a depth not penetrating left-side member 17 and right-side member 18. A bolt is inserted through hole 25 formed in second mount member 20 and engaged in screw tap hole 15 through screwing with an inner wall face thereof, and accordingly, left-side member 17, right-side member 18 and second mount member 20 are fixed together through bolts.

With reference to FIG. 7, a width-direction member 19 is fixed on width-direction roof beam 9 a. Similar to width-direction roof beam 9 a, width-direction member 19 is arranged to have the longitudinal direction thereof extending in the width direction of cab 1. Thereby, second mount member 20 has two lateral edges thereof supported by left-side member 17 and right-side member 18, and has the rear edge thereof further supported by width-direction member 19. Left-side member 17, right-side member 18 and width-direction member 19 constitute first mount member 10. First mount member 10 is interposed between the roof beams of cab 1 and second mount member 20.

Width-direction member 19 is formed with a plurality of screw tap holes 16. Screw tap holes 16 are formed at positions in respective correspondence with holes 26 formed in second mount member 20. Screw tap holes 16 are formed by boring from the upper surface of width-direction member 19 downward to a depth not penetrating width-direction member 19. A bolt is inserted through hole 26 formed in second mount member 20 and engaged in screw tap hole 16 through screwing with an inner wall face thereof, and accordingly, second mount member 20 and width-direction member 19 are fixed together through bolts.

First mount member 10 is fixed on the roof beams of cab 1, second mount member 20 is fixed on first mount member 10, and positioning antenna 50 is mounted on second mount member 20. Thus, positioning antenna 50 is mounted above roof plate 2 of cab 1 through the intermediary of first mount member 10 and second mount member 20. First mount member 10 and second mount member 20 constitute a mount unit for installing positioning antenna 50 above roof plate 2.

FIG. 8 illustrates a sectional view along a line VIII-VIII in FIG. 6. With reference to FIG. 8, roof plate 2 is fixed directly on the upper surfaces of left-side roof beam 7 and width-direction roof beam 9 a. Second mount member 20 is supported by left-side roof beam 7 and right-side roof beam 8 through the intermediary of left-side member 17 and right-side member 18 which is not shown in FIG. 8. Second mount member 20 includes a top plate 21. Top plate 21 has a planar shape and includes an upper primary surface, i.e., an antenna installation surface 21 a, and a lower primary surface, i.e., a rear surface 21 b. Antenna installation surface 21 a forms the upper surface of second mount member 20 and has a planar shape. Positioning antenna 50 is mounted on antenna installation surface 21 a.

Second mount member 20 further includes a horizontal support member 24 supporting top plate 21 from the side of rear surface 21 b thereof. Horizontal support member 24 is arranged to have the longitudinal direction thereof extending in the width direction (lateral direction) of cab 1. In the vertical direction, horizontal support member 24 is disposed on left-side member 17. Top plate 21 is disposed on horizontal support member 24. Thereby, a hollow gap G is formed between rear surface 21 b of top plate 21 included in second mount member 20 and roof plate 2. Since gap G is formed between second mount member 20 and roof plate 2, second mount member 20 is disposed without contacting roof plate 2.

Antenna main body 51 of positioning antenna 50 is disposed at the side of antenna installation surface 21 a of top plate 21. Antenna cable 56 connected to antenna main body 51 is disposed in such a way that it is inserted into through hole 27 formed in second mount member 20, extends in the lateral direction of cab 1 to pass across gap G below second mount member 20 to antenna cable outdrawing member 28. A part of antenna cable 56 is disposed in gap G between top plate 21 of second mount member 20 and roof plate 2. Antenna cable 56 is retained in gap G by a plurality of retaining members disposed on rear surface 21 b of top plate 21. Antenna cable 56 extends from gap G below second mount member 20 to the outside of the side surface of cab 1 via through hole 29 formed in antenna cable outdrawing member 28.

With reference to FIG. 9, roof plate 2 is fixed directly on the upper surfaces of left-side roof beam 7 and width-direction roof beam 9 a. Left-side roof beam 7 has a pipe structure, and has a deformed-pipe shape whose cross-sectional shape is non-circular but bent and complicated. Thereby, left-side roof beam 7 has a section stiffness stronger than roof plate 2. Left-side member 17 is welded on the upper surfaces of left-side roof beam 7, and thereby, left-side member 17 is fixed integrally to left-side roof beam 7. Left-side member 17 is disposed to protrude upward relative to the upper surface of left-side roof beam 7. Left-side member 17 is fixed directly on left-side roof beam 7 at a position on the surface of left-side roof beam 7 without overlapping with roof plate 2. Left-side member 17 is disposed leftward to the left edge of roof plate 2. The upper surface of left-side member 17 is configured to be higher than the upper surface of roof plate 2 in the vertical direction.

In FIG. 9, the structure at the left side of cab 1 is illustrated; however, at the right side of cab 1, a structure is formed in line symmetry to the structure at the left side with respect to a line extending in the vertical direction in FIG. 9. Specifically, similar to left-side roof beam 7 illustrated in FIG. 9, right-side roof beam 8 has a pipe structure and the pipe has a sectional shape of a deformed pipe. Similar to left-side member 17 illustrated in FIG. 9, right-side member 18 is welded on and fixed integrally to right-side roof beam 8, and the upper surface thereof is configured to be higher than the upper surface of roof plate 2 in the vertical direction.

With reference to FIG. 10, roof plate 2 is fixed directly on the upper surfaces of width-direction roof beam 9 a and right-side roof beam 8. Width-direction roof beam 9 a has a pipe structure which has a hollow space inside and the pipe is a deformed pipe having a sectional shape which is non-circular but bent and complicated. Thereby, width-direction roof beam 9 a has a section stiffness stronger than roof plate 2. Width-direction member 19 is welded on the upper surface of width-direction roof beam 9 a, and thereby, width-direction member 19 is fixed integral to width-direction roof beam 9 a. Width-direction member 19 is disposed to protrude upward relative to the upper surface of width-direction roof beam 9 a. Width-direction member 19 is fixed directly on width-direction roof beam 9 a at a position on the surface of width-direction roof beam 9 a without overlapping with roof plate 2. Width-direction member 19 is disposed rearward to the rear edge of roof plate 2. The upper surface of width-direction member 19 is configured to be higher than the upper surface of roof plate 2 in the vertical direction.

With reference to FIG. 11, second mount member 20 includes top plate 21 described above. Top plate 21 has a rectangle shape in planar view. The plate forming top plate 21 is bent at each side of the rectangle to form fin-shaped portions 22. Fin-shaped portion 22 forms an outer circumferential surface of second mount member 20. Second mount member 20 further includes a lateral pair of vertical support members 23 extending in the anteroposterior direction of cab 1 and a plurality of horizontal support members 24 extending in the lateral direction of cab 1. Vertical support members 23 and horizontal support members 24 are assembled to form an integral frame structure, and top plate 21 is mounted on the frame structure.

The paired vertical support members 23 are mounted on left-side member 17 and right-side member 18, respectively. Holes 25 are formed to penetrate both top plate 21 and vertical support members 23, and as described above, top plate 21 and vertical support members 23 are fixed to left-side member 17 and right-side member 18 through bolts.

Horizontal support members 24 include a horizontal support member 24 a mounted on width-direction member 19. Holes 26 are formed to penetrate both top plate 21 and horizontal support member 24 a, and as described above, top plate 21 and horizontal support member 24 a are fixed to width-direction member 19 through bolts.

Horizontal support members 24 are provided in the same number as that of holes 25 formed in vertical support members 23. Horizontal support members 24 are installed to vertical support members 23 at positions where holes 25 are formed in vertical support member 23. The plurality of horizontal support members 24 are arranged with an equal interval between each other in the anteroposterior direction of cab 1.

Hereinafter, the effects of the present embodiment will be described.

In the present embodiment, as illustrated in FIG. 5, positioning antenna 50 is disposed above roof plate 2 of cab 1. The disposition of positioning antenna 50 on the roof portion of cab 1 enables positioning antenna 50 to be easily disposed at the highest position in bulldozer 30, which thereby improves the positioning accuracy of the present position of the work implement by means of positioning antenna 50.

Cab 1 as a whole is mounted on the main body of the work vehicle with a vibration absorber interposed therebetween to absorb vibrations, and thereby, the vibrations transferred to the structural materials of cab 1 can be suppressed. Accordingly, it is possible to prevent positioning antenna 50 itself from vibrating, which thereby prevents the positioning accuracy from being decreased by vibrations, and as a result, it is possible to further improve the positioning accuracy of positioning antenna 50 and prevent positioning antenna 50 from damage as well.

Positioning antenna 50 is mounted on the roof portion of cab 1 with first mount member 10 and second mount member 20 interposed therebetween. First mount member 10 includes left-side member 17 fixed on left-side roof beam 7 and right-side member 18 fixed on right-side roof beam 8. Left-side roof beam 7 and right-side roof beam 8 are welded together to form a rigid structure body for the roof of cab 1. Left-side roof beam 7 and right-side roof beam 8 are also a part of the rollover protection structure of cab 1, which means they are forming a rigid structure at this point of view.

Second mount member 20 is disposed above roof plate 2 across left-side member 17 and right-side member 18, and positioning antenna 50 is installed on second mount member 20, and thereby, positioning antenna 50 is supported by the roof beams which is a rigid structure. Accordingly, it is possible to prevent the position of positioning antenna 50 from being varied by the vibrations of roof plate 2, which makes it possible to locate positioning antenna 50 accurately relative to the structural materials of cab 1. Thereby, it is possible to install positioning antenna 50 above roof plate 2 at an accurate position and in a proper attitude, improving the positioning accuracy of positioning antenna 50 and the reliability of positioning antenna 50.

In the present embodiment as illustrated in FIG. 4, it is acceptable that roof plate 2 is convexly curved upward. By forming roof plate 2 into a convex structure, it is possible to prevent water from being accumulated on upper surface 2 a of roof plate 2. Since positioning antenna 50 is installed above roof plate 2 through the intermediary of first mount member 10 and second mount member 20, it is possible to prevent the convexly curving shape of roof plate 2 from interfering with the disposition of positioning antenna 50. Thereby, positioning antenna 50 can be installed above roof plate 2 at an accurate position and in a proper attitude with more certainty.

As illustrated in FIG. 8, it is acceptable that gap G is formed between second mount member 20 and roof plate 2. Thereby, it is possible to prevent with more certainty the vibrations of roof plate 2 from affecting the position of positioning antenna 50, which makes it possible to install positioning antenna 50 above roof plate 2 at an accurate position with more certainty. Even though roof plate 2 is formed into a convex shape, second mount member 20 is disposed without contacting roof plate 2, and thereby, it is possible to prevent roof plate 2 from interfering with second mount member 20. Accordingly, it is possible to install positioning antenna 50 on second mount member 20 in more proper attitude.

It is acceptable that a part of antenna cable 56 connected to positioning antenna 50 is disposed in gap G between second mount member 20 and roof plate 2. Thereby, antenna cable 56 can be protected by second mount member 20 from the outer environment, improving operation life of antenna cable 56. Moreover, since a part of antenna cable 56 is disposed below second mount member 20, the part of antenna cable 56 covered by second mount member 20 is invisible from the outside. Thereby, it is possible to make the outer appearance of the work vehicle look better.

In gap G, antenna cable 56 is retained to the side of rear surface 21 b of top plate 21 of second mount member 20. Thereby, it is possible to prevent antenna cable 56 from being shaken to collide with roof plate 2 or horizontal support member 24 or the like at times when the work vehicle is moving or similar situations, which makes it possible to improve reliability of antenna cable 56.

As illustrated in FIG. 7, it is acceptable that left-side member 17 and right-side member 18 are welded on the upper surfaces of left-side roof beam 7 and right-side roof beam 8, respectively. Since left-side roof beam 7 and right-side roof beam 8 are structural materials constituting cab 1, in order to prevent the strength of cab 1 itself from being decreased, it is required to keep the strength of left-side roof beam 7 and right-side roof beam 8. Fixing left-side member 17 and right-side member 18 through welding saves the need of performing additional processing on left-side roof beam 7 and right-side roof beam 8 in order to fix left-side member 17 and right-side member 18. Thereby, it is possible to keep the strength of left-side roof beam 7 and right-side roof beam 8, preventing the strength of cab 1 from being decreased with certainty.

The term “welding” mentioned above refers to any processing by which it is possible to integrate left-side member 17 and right-side member 18 with the upper surfaces of left-side roof beam 7 and right-side roof beam 8, respectively, without decreasing the strength of left-side roof beam 7 and right-side roof beam 8. Thereby, the term is not limited to welding in narrow definition that heat and/or pressure are applied to at least one of left-side member 17 and left-side roof beam 7 to join the two through welding. In other words, it is acceptable to join left-side member 17 and left-side roof beam 7 through the use of a filler material or through pressure welding or soldering.

Screw tap holes 15 are formed in left-side member 17 and right-side member 18 included in first mount member 10 to a depth not penetrating left-side member 17 and right-side member 18 in the vertical direction thereof and thereby to have a bottom, and second mount member 20 is fixed to first mount member 10 through bolt-screwing. Thereby, it is possible to prevent such processing as perforating holes or the like in left-side roof beam 7 and right-side roof beam 8 so as to install second mount member 20, which thereby keeps the strength of left-side roof beam 7 and right-side roof beam 8 with more certainty.

As illustrated in FIG. 7, it is acceptable that width-direction roof beam 9 a or 9 b is disposed on the top of cab 1, extending in the lateral direction, and width-direction member 19 is fixed on width-direction roof beam 9 a or 9 b so as to support second mount member 20. Thereby, second mount member 20 is supported not only by left-side member 17 and right-side member 18 but also by width-direction member 19 extending in the lateral direction of cab 1. Since first mount member 10 becomes a more rigid structure, it is possible for first mount member 10 to support second mount member 20 more stably. Consequently, it is possible to have second mount member 20 disposed above roof plate 2 more stably.

As illustrated in FIG. 8, it is acceptable that second mount member 20 includes antenna installation surface 21 a having a planar shape and positioning antenna 50 is mounted on antenna installation surface 21 a. Thereby, positioning antenna 50 is installed on a flat plane, which makes it easier to mount positioning antenna 50 on antenna installation surface 21 a at an accurate position and in a proper attitude.

As illustrated in FIG. 11, second mount member 20 includes the lateral pair of vertical support members 23 extending in the anteroposterior direction of cab 1 and the plurality of horizontal support members 24 extending in the lateral direction of cab 1 for joining the pair of vertical support members 23. Thereby, the strength of second mount member 20 is improved. Second mount member 20 is configured to have a rigidity sufficient enough to prevent flexure from occurring when it is disposed across left-side member 17 and right-side member 18. Thereby, it is possible to prevent with certainty second mount member 20 from deformation by curving downward to interfere with roof plate 2, further enabling positioning antenna 50 to be mounted above roof plate 2 at an accurate position and in a proper attitude.

If the rigidity of second mount member 20 is small, when bulldozer 30 is in traveling or in operation through using dozing blade 38, second mount member 20 may vibrate. The vibrations of second mount member 20 will fluctuate the position of positioning antenna 50 mounted on second mount member 20, and as a result, positioning antenna 50 is deviated from an initially calibrated position, which decreases the positioning accuracy of positioning antenna 50 in determining the present position of the work implement. Thus, as illustrated in FIG. 11, second mount member 20 is reinforced by the plurality of horizontal support members 24. As a result, it is possible to improve the rigidity of second mount member 20, preventing second mount member 20 from vibrating, and thereby, it is possible to prevent positioning antenna 50 mounted on second mount member 20 from vibrating, making it possible to improve the positioning accuracy of positioning antenna 50.

In the above embodiment, each of left-side member 17 and right-side member 18 is formed into a single member extending in the anteroposterior direction of cab 1; however, it is acceptable that each of left-side member 17 and right-side member 18 is formed from a plurality of members being separated with an interval in the anteroposterior direction of cab 1. Similarly, it is acceptable that width-direction member 19 is formed from a plurality of members being separated with an interval in the width direction of cab 1. The disposition of intervals can prevent first mount member 10 from damming rain water flowing from the central portion of roof plate 2 toward the edges thereof, making it less likely that water is accumulated on roof plate 2. However, fixing a plurality of members on the roof beam reduces the working efficiency of fixing first mount member 10, and the disposition of intervals decreases the strength of first mount member 10. In consideration of these facts, it is preferred to optimize the design of first mount member 10.

In the above embodiment, welding is described as an example of preferable approaches for fixing first mount member 10 on the roof beam; however, the fixing approach is not limited thereto. In the case that it is possible to prevent the strength of the roof beam from being decreased and keep the fixed strength of first mount member 10 to the roof beam sufficient, it is acceptable to adopt any other approach such as adhesion or the like to fix first mount member 10 to the roof beam.

In the above embodiment, although it is described that width-direction member 19 is disposed at the rear side of cab 1 and the rear edge of second mount member 20 is supported by width-direction member 19, it is acceptable to dispose width-direction member 19 at an arbitrary position in the anteroposterior direction of cab 1. For example, it is acceptable to dispose a width-direction member to support the front edge of second mount member 20, it is acceptable to dispose the width-direction member to support a middle portion of second mount member 20 in the anteroposterior direction, and it is also acceptable to dispose a plurality of width-direction members.

It is possible to support second mount member 20 more stably on first mount member 10 by inserting a bolt through horizontal support member 24 configured to improve the rigidity of second mount member 20 to fix second mount member 20 on width-direction member 19. In this regard, it is preferable to optimize the designs of first mount member 10 and second mount member 20 so as to dispose width-direction members 19 and horizontal support members 24 overlapping each other at positions in the anteroposterior direction of cab 1.

If second mount member 20 is offered with a sufficiently great rigidity, it is possible that second mount member 20 will not flex even when the lateral edges thereof are supported by left-side member 17 and right-side member 18 respectively. In this case, the width-direction member disposed on the roof beam of cab 1 may be omitted.

In the above embodiment, bulldozer 30 is described as an example of the work vehicle; however, the work vehicle of the present invention is not limited to a bulldozer, and it may be another work vehicle such as a wheel loader, a motor grader or the like.

It should be understood that the embodiments disclosed herein have been presented for the purpose of illustration and description but not limited in all aspects. It is intended that the scope of the present invention is not limited to the description above but defined by the scope of the claims and encompasses all modifications equivalent in meaning and scope to the claims.

REFERENCE SIGNS LIST

1: cab; 2: roof plate; 2 a: upper surface; 2 b: lower surface; 7: left-side roof beam; 8: right-side roof beam; 9 a, 9 b: width-direction roof beam; 10: first mount member; 15, 16: screw tap hole; 17: left-side member; 18: right-side member; 19: width-direction member; 20: second mount member; 21: top plate; 21 a: antenna installation surface; 21 b: rear surface; 22: fin-shaped portion; 23: vertical support member; 24, 24 a: horizontal support member; 25, 26: hole; 27, 29: through hole; 28: antenna cable outdrawing member; 30: bulldozer; 38: dozing blade; 50: positioning antenna; 51: antenna main body; 52: support member; 56: antenna cable; G: gap; OP: operator 

1. A work vehicle comprising: a work implement; a cab to be boarded with an operator to operate said work implement, said cab including a lateral pair of roof beams disposed respectively on the top of both side surfaces of said cab and a roof plate supported respectively by said pair of roof beams; a first mount member including a left-side member fixed on said roof beam at the left side and a right-side member fixed on said roof beam at the right side; a second mount member disposed above said roof plate across said left-side member and said right-side member; and a positioning antenna mounted on said second mount member.
 2. The work vehicle according to claim 1, wherein said roof plate is convexly curved upward.
 3. The work vehicle according to claim 1, wherein a gap is formed between said second mount member and said roof plate.
 4. The work vehicle according to claim 3, further comprising an antenna cable connected to said positioning antenna, wherein a part of said antenna cable is disposed inside said gap.
 5. The work vehicle according to claim 1, wherein said left-side member and said right-side member are welded on upper surfaces of said roof beams.
 6. The work vehicle according to claim 1, wherein said cab further includes a width-direction roof beam disposed on the top of said cab and extending in the width direction of said work vehicle, said first mount member further includes a width-direction member fixed on said width-direction roof beam, and said second member is supported by said width-direction member.
 7. The work vehicle according to claim 1, wherein said second mount member has an antenna installation surface, and said positioning antenna is mounted on said antenna installation surface, and said antenna installation surface has a planar shape. 